Photoresists are photosensitive films for transfer of images to a substrate. They form negative or positive images. After coating a photoresist on a substrate, the coating is exposed through a patterned photomask to a source of activating energy, such as ultraviolet light, to form a latent image in the photoresist coating. The photomask has areas opaque and transparent to activating radiation that define an image desired to be transferred to the underlying substrate.
Known photoresists can provide features having resolution and size sufficient for many existing commercial applications. However for many other applications, the need exists for new photoresists that can provide highly resolved images of sub-quarter-micron (<0.25 μm) dimension.
Various attempts have been made to alter the make-up of photoresist compositions to improve performance of functional properties. Among other things, a variety of basic compounds have been reported for use in photoresist compositions. See U.S. Pat. Nos. 7,479,361; 7,534,554; and 7,592,126. See also U.S. 2011/0223535 and US 2012/0077120.